WO2019138752A1

WO2019138752A1 - Fuse element

Info

Publication number: WO2019138752A1
Application number: PCT/JP2018/045172
Authority: WO
Inventors: 吉弘米田
Original assignee: デクセリアルズ株式会社
Priority date: 2018-01-10
Filing date: 2018-12-07
Publication date: 2019-07-18
Also published as: CN111527580B; TW201933409A; JP2019121550A; US20210074502A1; KR20200085896A; KR102442404B1; CN111527580A; JP7010706B2

Abstract

In order to maintain insulating performance while using a fuse element of a substantial size to improve rating, the present invention has: a fuse element 2; and a case 3 that accommodates the fuse element 2, wherein the case 3 has, on at least a portion of an inner wall surface 8a facing an inner section 8 accommodating the fuse element 2, a resin part 4 having a surface that is melted by heat accompanying the fusion-cutting of the fuse element 2.

Description

Fuse element

The present technology relates to a fuse element mounted on a current path, which fuses a fuse element by self-heating when a current exceeding the rating flows and cuts off the current path, particularly a fuse which can be used for high rated and large current applications It relates to an element.
This application claims priority based on Japanese Patent Application No. 2018-001900 filed on Jan. 10, 2018 in Japan, and this application is incorporated herein by reference. It is incorporated.

2. Description of the Related Art Conventionally, a fuse element is used which is melted by self-heating when a current exceeding the rating flows, and cuts off the current path. As the fuse element, for example, a holder fixed fuse in which solder is sealed in a glass tube, a chip fuse in which an Ag electrode is printed on the surface of a ceramic substrate, a screw which thins a part of copper electrode and is incorporated in a plastic case Plug-in fuses and the like are often used.

However, it has been pointed out that the above-mentioned existing fuse element has a low current rating, and has a problem that it is inferior in rapidity if the rating is increased due to an increase in size.

In addition, when a fast-acting fuse element for reflow mounting is assumed, a Pb-containing high melting point solder having a melting point of 300 ° C. or higher is generally preferable for the melting element so as not to melt by the heat of reflow. However, in the RoHS directive and the like, the use of Pb-containing solder is only recognized as limited, and it is thought that the demand for Pb-free will be strengthened in the future.

That is, the fuse element is required to be able to cope with a large current by raising its rating, and to have a quick-breaking property for rapidly interrupting the current path when the overcurrent exceeds the rating.

Therefore, a fuse element is proposed in which a fuse element is mounted between the first and second electrodes on an insulating substrate provided with the first and second electrodes (see Document 1).

When the fuse element described in Document 1 is mounted on a circuit board or the like, the fuse element is incorporated in a part of the current path between the first and second electrodes, and it is self-powered when a current of a value higher than the rating flows. The heat generation melts the fuse element and cuts off the current path.

JP, 2014-209467, A

Here, the applications of this type of fuse element are extended from electronic devices to high current and high voltage applications such as industrial machines, electric bicycles, electric bikes, and cars. Therefore, with the increase in capacity and rating of electronic devices and battery packs to be mounted, the fuse element is required to further improve the current rating.

In order to increase the current rating, it is effective to reduce the resistance by increasing the size of the fuse element. However, in order to increase the current rating of the fuse element, it is necessary to balance the reduction of the conductor resistance of the fuse element with the insulation performance at the time of breaking the current path. That is, in order to pass more current, the conductor resistance needs to be lowered, and thus the cross-sectional area of the fuse element needs to be increased. On the other hand, as shown in FIGS. 15A and 15B, when the current path is cut off, the metal body 80a constituting the fuse element 80 is scattered around due to the arc discharge generated, and the current path 81 is newly formed. It may be formed, the larger the cross-sectional area of the fuse element, the higher the risk.

The ceramic material is used in many cases for housing the high current rating fuse element 80, but the ceramic material has high thermal conductivity and efficiently captures the high heat melting debris of the fuse element 80 (cold trap), As a result, a continuous conduction path is formed on the inner wall of the case.

In addition, in the conventional high-voltage compatible current fuse, complicated materials and processing processes are all required such as sealing of an arc extinguishing agent and manufacture of a helical fuse, and the miniaturization of the fuse element and the high rating of the current It is disadvantageous in terms of

As described above, a fuse that can maintain insulation performance while using a fuse element having a considerable size to improve the rating, and can realize miniaturization with a simple configuration and simplification of the manufacturing process Development of elements is desired.

In order to solve the problems described above, a fuse element according to the present technology has a fuse element and a case for housing the fuse element, and the case has an inner wall surface facing the inside for housing the fuse element. At least a portion of the resin portion has a resin portion whose surface is melted by heat accompanying melting of the fuse element.

Further, a fuse element according to the present technology has a fuse element and a case for housing the fuse element, and the case is provided on at least a part of the inner wall surface facing the inside for housing the fuse element. It has a resin part which catches the fusion scattering thing of an element.

According to the present technology, since at least a part of the inner wall surface of the case that accommodates the fuse element has the resin portion that captures the molten scattered matter of the fuse element, the fused scattered matter is captured by the resin portion. It is possible to prevent the continuous adhesion to the inner wall surfaces reaching both ends of the current flow direction. Therefore, according to the present invention, it is possible to prevent a situation in which both ends of the fused fuse element are short circuited by the melt spatter of the fuse element being continuously attached to the inner wall surface of the case.

FIG. 1 is a cross-sectional view showing a fuse element to which the present technology is applied, where (A) shows a state before the fuse element is melted and (B) shows a state after the fuse element is melted. FIG. 2 (A) is a cross-sectional view showing a state in which the melted and scattered matter is captured by the resin portion, and FIG. 2 (B) is not provided with the resin portion and a deposited layer of the melted and scattered matter is formed on the inner wall surface of the case. It is sectional drawing which shows a state. FIG. 3 is a cross-sectional view showing a modification of the fuse element to which the present technology is applied, in which (A) shows the fuse element before melting and (B) shows the fuse element after melting. FIG. 4 (A) is a SEM image of the inner wall surface of the case made of alumina (ceramic material), and FIG. 4 (B) is a state where the molten spatter of the fuse element adheres to the case made of alumina (ceramic material) FIG. 4 (C) is a SEM image which is a magnified image of the state in which the molten spatter of the fuse element adheres to the case made of alumina (ceramic material). FIG. 5 (A) is a SEM image of the inner wall surface of a case made of nylon 46 (a nylon resin material), and FIG. 5 (B) is a case where the fuse element is made of nylon 46 (a nylon resin material). FIG. 5C is a SEM image showing a state in which the melted and scattered matter is adhered, and FIG. 5C is a further enlarged view of a state in which the melted and scattered matter of the fuse element is adhered to a case made of nylon 46 (nylon resin material). SEM image. FIG. 6A is an external perspective view showing a fuse element having a laminated structure in which high melting point metal layers are laminated on the upper and lower surfaces of the low melting point metal layer, and FIG. It is an external appearance perspective view which shows the fuse element made into the coating structure which is exposed and outer periphery is coat | covered with a high melting point metal layer. FIG. 7 is a cross-sectional view showing a fuse element provided with a deformation restricting portion. FIG. 8 is a diagram showing a circuit configuration of the fuse element, in which (A) shows the state before the fuse element is melted and (B) shows the state after the fuse element is melted. FIG. 9 is a view showing a modified example of the fuse element to which the present technology is applied, (A) is an external perspective view, and (B) is a cross-sectional view. FIG. 10 is a view showing a state after melting of the modification of the fuse element shown in FIG. 9, (A) is an external perspective view in a state in which the cover member is removed, and (B) is a cross-sectional view. FIG. 11 is a cross-sectional view showing a modification of the fuse element to which the present technology is applied. FIG. 12 is a cross-sectional view showing a modification of the fuse element to which the present technology is applied. FIG. 13 is a view showing a modification of the fuse element to which the present technology is applied, (A) is a top view showing a base member having a heating element on which the fuse element is mounted, and (B) is a cross section FIG. FIG. 14 is a circuit diagram of the fuse element shown in FIG. 13, where (A) shows the state before the fuse element is melted and (B) shows the state after the fuse element is melted. FIG. 15 is a cross-sectional view showing a conventional fuse element, in which (A) shows the fuse element before melting and (B) shows the fuse element after melting.

Hereinafter, a fuse element to which the present technology is applied will be described in detail with reference to the drawings. The present technology is not limited to only the following embodiments, and it goes without saying that various modifications can be made without departing from the scope of the present technology. Further, the drawings are schematic, and the ratio of each dimension may be different from the actual one. Specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios among the drawings are included.

[Fuse element]
The fuse element 1 according to the present technology realizes a small-sized, high-rated fuse element and has a resistance value of 0 while having a small planar dimension of 3 to 5 mm × 5 to 10 mm and a height of 2 to 5 mm. The rating is increased to 2 to 1 mΩ, 50 to 150 A rating. Of course, the present invention can be applied to a fuse element having any size, resistance value and current rating.

The fuse element 1 to which the present technology is applied has a fuse element 2 and a case 3 for housing the fuse element 2 as shown in FIGS. 1 (A) and (B). Both ends of the fuse element 2 in the current supply direction of the fuse element 2 are led out from the outlet 7 of the case 3. The fuse element 2 has

terminal portions

2a and 2b which are extended outward from the both ends led out from the outlet 7 and connected to connection electrodes of an external circuit (not shown). In the fuse element 1, the

terminal portions

2a and 2b are connected to the terminals of the circuit in which the fuse element 1 is incorporated, thereby constituting a part of the current path of the circuit. The fuse element 2 is melted by self-heating (Joule heat) when a current exceeding the rating flows, and cuts off the current path of the circuit in which the fuse element 1 is incorporated.

The

terminal portions

2a and 2b of the fuse element 2 and the connection electrodes of the external circuit can be performed by a known method such as solder connection. In addition, the fuse element 1 may connect the

terminal portions

2a and 2b to a metal plate serving as an external connection terminal capable of handling a large current. The connection between the

terminal portions

2a and 2b of the fuse element 2 and the metal plate may be made by a connecting material such as solder, or the

terminal portions

2a and 2b may be held by clamp terminals connected to the metal plate. Or you may carry out by screwing

terminal part

2a, 2b or a clamp terminal to a metal plate with the screw which has conductivity.

[Case]
The case 3 can be formed of an insulating member such as engineering plastic, alumina, glass ceramics, mullite, or zirconia, and the case 3 can be formed by molding, powder molding, or the like depending on the material. Manufactured.

Further, as shown in FIG. 1, the case 3 is provided with a lead-out port 7 for leading out both end portions of the fuse element 2 to be accommodated in the conduction direction. The outlet 7 is formed on opposite wall portions of the case 3 to support both end portions of the fuse element 2 in the current-flowing direction and to be hollow in the storage space 8 in the case 3.

Here, the case 3 is preferably formed of a ceramic material such as alumina having a relatively high thermal conductivity. The case 3 uses the ceramic material having excellent thermal conductivity to efficiently dissipate the heat generated by the fuse element 2 to the outside, and locally heats and melts the hollow held fuse element 2. It can be done. Therefore, the fuse element 2 is fused at only a limited portion, and the amount and the adhesion area of the fused and scattered matter also become limited.

[Resin department]
The case 3 for housing the fuse element 2 has a storage space 8 for housing the fuse element 2 and melting and scattering that occurs when the fuse element 2 is melted and disconnected on at least a part of the inner wall surface 8a facing the fuse element 2 It has the resin part 4 which captures a thing. The resin portion 4 is, for example, around the fuse element 2 at a position opposite to the middle position of the fuse element 2 housed in the case 3 of the inner wall surface 8 a in the current-carrying direction. Is formed over the entire circumference of the inner wall surface 8a surrounding the. Thus, the resin portion 4 blocks the inner wall surface 8a extending between the pair of outlet ports 7 supporting the fuse element 2 in the hollow in the housing space 8 in the direction orthogonal to the energization direction of the fuse element. Is formed.

The resin portion 4 captures the molten scattered matter 11 as shown in FIG. 2A when the molten scattered matter 11 at a high temperature adheres to the fused element 2 at the time of melting. Because of the high heat, the resinous part 4 is melted and a part of the many scattered scattered matters 11 intrude inside.

Further, on the surface of the resin portion 4, the molten scattered matter 11 is less likely to be cooled than the ceramic material, and the molten scattered matter 11 is aggregated and enlarged due to heat of the molten scattered matter 11 itself or radiant heat accompanying melting of the fuse element 2. Do. Furthermore, a part of the molten scattered matter 11 captured by the frequent scattered flow of the molten scattered matter 11 is released.

As a result, in the case 3, the molten scattered matter 11 does not deposit and continue on the resin portion 4, and the resin portion 4 electrically insulates between the two end portions of the fuse element 2 led out from the outlet 7. Be done. Therefore, in the fuse element 1, both ends of the fuse element 2 in the conduction direction are short-circuited by the molten scattered matter 11 of the fuse element 2 even when the molten scattered matter 11 of the fuse element 2 adheres to the inner wall surface 8a of the case 3. The situation can be prevented and high insulation resistance can be maintained.

The resin portion 4 is formed by using a material which captures the high temperature molten scattered matter 11 and melts due to the high heat of the molten scattered matter 11, and a part of the molten scattered matter 11 intrudes into the inside of the resin portion 4 Is formed using a material having a melting point of 400 ° C. or less, more preferably a reflow temperature (eg, 260 ° C.) or more, or preferably formed using a material having a thermal conductivity of 1 W / m · K or less .

The material of the resin portion 4 is, for example, nylon (nylon 46, nylon 66, nylon 6, nylon 4T, nylon 6T, nylon 9T, nylon 10T, etc.) or fluorinated (PTFE, PFA, FEP, ETFE, EFEP, CPT, etc.) It can form using the resin material of PCTFE etc.).

In addition, the resin portion 4 can be formed on the inner wall surface 8a of the case 3 according to the material by application, printing, vapor deposition, sputtering, or another known method for forming a resin film or resin layer. Moreover, the resin part 4 may be formed with one type of resin material, and may be formed by laminating a plurality of types of resin materials.

The resin portion 4 can be efficiently insulated by forming it at a position facing the middle position of the fuse element 2 in the direction of energization as shown in FIG. When an overcurrent exceeding the rating flows and the fuse element melts due to self-heating, heat is dissipated from the outlet 7 supporting both ends of the fuse element 2 in the direction of energization, so the fuse element 2 most distant from the outlet 7 is energized. It is easy to overheat and melt at an intermediate position in the direction. Therefore, the molten scattered matter 11 can be reliably captured by arranging the resin portion 4 at a position facing the intermediate position.

Further, as shown in FIGS. 3A and 3B, the resin portion 4 may be formed over the entire surface of the inner wall surface 8 a of the case 3. In addition, the formation position and formation pattern of the resin part 4 formed in the inner wall surface 8a of case 3 can be designed arbitrarily.

Tracking resistance
Here, in the fuse element 2, the amount of heat generation at the time of the self heat generation interruption due to the overcurrent also increases with the improvement of the current rating, so the heat influence on the case 3 also increases. For example, when the current rating of the fuse element rises to the 100 A level and the rated voltage rises to the 60 V level, the surface of the case 3 facing the fuse element 2 and the resin portion 4 carbonize due to arc discharge at the time of current interruption. There is also a concern that leak current may flow to lower the insulation resistance, or fire may occur to damage the element housing, or to shift or drop off the mounting substrate.

As a measure to stop the arc discharge immediately and shut off the circuit, a hollow case filled with an arc extinguishing agent, or a high voltage current that generates a time lag by spirally winding the fuse element around the heat dissipation material A fuse has also been proposed. However, conventional high-voltage current fuses require complicated materials and processing processes, such as arc extinguishing agent encapsulation and spiral fuse manufacture, so that miniaturization of the fuse element and high current rating It is disadvantageous in terms of

Therefore, in the fuse element 1, the resin portion 4 is preferably formed of a material having a tracking resistance of 250 V or more. This prevents carbonization of the resin part 4 even by increasing the scale of the arc discharge at the time of heat generation interruption due to the overcurrent due to the improvement of the current rating, and reduces the insulation resistance due to the occurrence of leakage current or Case 3 due to ignition. It can prevent damage.

As a material which has the tracking resistance which comprises the resin part 4, a nylon-type material is preferable. By using a nylon-based plastic material, the tracking resistance of the resin portion 4 can be made 250 V or more. Tracking resistance can be determined by a test based on IEC60112.

Among the nylon-based plastic materials constituting the resin portion 4, it is preferable to use nylon 46, nylon 6T, and nylon 9T, in particular. Thereby, the resin part 4 can improve tracking resistance to 600 V or more.

[Insulation resistance]
In addition, as described above, the case 3 is thermally conductive in that it locally heats and melts the hollow held fuse element 2 to limit the amount of molten scattered matter and the adhesion area to a limited level. It is preferable to be formed of an excellent ceramic material. On the other hand, since the case 3 made of ceramic material is excellent in thermal conductivity, it is rapidly cooled when the high temperature molten scattered matter 11 adheres to the inner wall surface 8a of the case 3, as shown in FIG. A deposit layer of the molten scattered matter 11 is easily formed, and there is a possibility that a leak current may be generated across the

terminal portions

2a and 2b of the fuse element 2 through the deposited molten scattered matter 11.

Therefore, as shown in FIG. 2A, the fuse element 1 captures the melting and scattering object 11 by forming the resin portion 4, and the radiation heat and the melting and scattering object 11 caused by the melting of the resin portion 4. By melting together with the molten scattered matter 11 due to high heat, the formation of a deposit layer by the molten scattered matter 11 can be suppressed.

That is, by using case 3 made of a ceramic material, fuse element 1 locally heats and melts fuse element 2 held in the hollow, thereby suppressing the amount and the adhesion area of the fused and scattered matter to a limited one. At the same time, the molten scattered matter 11 is captured by the resin portion 4 and the resin portion 4 is melted, thereby preventing the formation of the deposited layer of the molten scattered matter 11 and preventing the generation of the leak current to achieve high insulation resistance (eg 10 ¹³ kΩ level) can be maintained.

[Example]
FIG. 4 (A) is a SEM image of the inner wall surface of the case made of alumina (ceramic material), and FIG. 4 (B) is the case where the melting spatter 11 of the fuse element 2 adheres to the case made of alumina (ceramic material) FIG. 4C is a SEM image obtained by further enlarging the state in which the molten scattered matter 11 of the fuse element 2 is attached to the case made of alumina (ceramic material). FIG. 5A is a SEM image of the inner wall surface of a case made of nylon 46 (a nylon resin material), and FIG. 5 (B) is a fuse element 2 in the case made of nylon 46 (a nylon resin material). FIG. 5 (C) is a SEM image showing a state in which the molten scattered matter 11 of the present invention adheres, and FIG. 5C shows a state in which the molten scattered matter 11 of the fuse element 2 is attached to the case made of nylon 46 (nylon resin material). It is a magnified SEM image.

As shown in FIGS. 4 (B) and 4 (C), it can be seen that the molten scattered matter 11 is closely attached to the alumina surface to form a deposited layer.

On the other hand, as shown in FIGS. 5B and 5C, the molten scattered matter 11 of the fuse element 2 adheres sparsely to the surface of the nylon 46, and the radiant heat accompanying melting and the heat of the molten scattered matter 11 cause the nylon 46 to It can be seen that a void formed by melting the surface of is formed. As described above, the molten scattered matter 11 does not continuously deposit on the surface of the resin material, and the leaked scattered matter 11 penetrates the void formed by the depression of the resin material, thereby forming a leak current path. It is difficult.

When the insulation resistance of the case shown in FIGS. 4 and 5 was measured (cut-off condition: 300 A / 62 V), the insulation resistance of the alumina case shown in FIG. 4 dropped to 80 kΩ while the nylon shown in FIG. The insulation resistance of the 46 case was 1.8 × 10 ¹³ kΩ.

The case made of nylon 46 has excellent insulation resistance, but the resin such as nylon 46 has low thermal conductivity, so the heat generated by the fuse element 2 can not be dissipated efficiently, and the melting area of the fuse element 2 becomes wide. . Therefore, a large amount of molten scattered matter 11 is scattered, and the adhesion area to the inner surface of the case is also wide. Therefore, in order to maintain high insulation resistance when downsizing of the fuse element is to be achieved in addition to the high rating, the amount of the fused and scattered matter 11 is minimized and the adhesion region to the inner surface of the case is also limited. Is desirable.

In this respect, as described above, the fuse element 1 locally heats and melts the fuse element 2 held in the hollow by using the case 3 made of the ceramic material, and the amount of the molten scattered matter and the adhesion area are While suppressing the material to be limited, the resin portion 4 captures the molten scattered matter 11 and the resin portion 4 melts, thereby preventing the formation of the deposited layer of the molten scattered matter 11 and preventing the generation of the leak current. It is advantageous because it can maintain high insulation resistance (e.g. 10 ¹³ kΩ level).

[Fuse element]
Next, fuse element 2 will be described. The fuse element 2 is a low melting point metal such as Pb-free solder mainly composed of solder or Sn, or a laminate of a low melting point metal and a high melting point metal. For example, as shown in FIG. 6, the fuse element 2 is a laminated structure including an inner layer and an outer layer, and the high melting point metal layer 10 is formed as the outer layer laminated on the low melting metal layer 9 as the inner layer and the low melting metal layer 9. Have.

The low melting point metal layer 9 is preferably a metal containing Sn as a main component, and is a material generally called “Pb free solder”. The melting point of the low melting point metal layer 9 is not necessarily higher than the reflow temperature (for example, 260 ° C.), and may be melted at about 200 ° C. The high melting point metal layer 10 is a metal layer laminated on the surface of the low melting point metal layer 9, and is made of, for example, Ag, Cu, or a metal containing any of these as a main component. Have a high melting point which does not melt even when mounted on an external circuit board.

Even if the reflow temperature exceeds the melting temperature of the low melting point metal layer 9 by laminating the high melting point metal layer 10 as the outer layer on the low melting point metal layer 9 to be the inner layer, the fuse element 2 is a fuse element It does not lead to melting as 2. Therefore, fuse element 1 can be efficiently mounted by reflow.

Further, the fuse element 2 does not melt even by self-heating while the predetermined rated current flows. Then, when a current having a value higher than the rating flows, self-heating starts melting from the melting point of the low melting point metal layer 9, and the current path between the

terminal portions

2a and 2b can be cut off promptly. For example, when the low melting point metal layer 9 is made of a Sn—Bi alloy, an In—Sn alloy, or the like, the fuse element 2 starts melting at a low temperature of about 140 ° C. or 120 ° C. At this time, the fuse element 2 is made of, for example, an alloy containing 40% or more of Sn as a low melting point metal, and the high melting point metal layer 9 is etched by melting the low melting point metal layer 9. 10 melts at a temperature lower than the melting temperature. Therefore, the fuse element 2 can be melted and cut in a short time by utilizing the erosion of the high melting point metal layer 10 by the low melting point metal layer 9.

Further, since the fuse element 2 is configured by laminating the high melting point metal layer 10 on the low melting point metal layer 9 to be the inner layer, the melting temperature is significantly reduced compared to a conventional chip fuse or the like made of high melting point metal. be able to. Therefore, fuse element 2 is formed to be wider than the high melting point metal element, and the conduction direction is shortened, thereby achieving miniaturization while greatly improving the current rating, and to the connection portion with the circuit board. Can reduce the effects of heat. In addition, it can be made smaller and thinner than conventional chip fuses having the same current rating, and is excellent in quick-breakability.

Further, fuse element 2 can improve the resistance (pulse resistance) to a surge in which an abnormally high voltage is instantaneously applied to the electrical system in which fuse element 1 is incorporated. That is, the fuse element 2 should not be melted down, for example, when a current of 100 A flows for several milliseconds. In this respect, since a large current flowing in a very short time flows in the surface layer of the conductor (skin effect), the fuse element 2 is provided with the high melting point metal layer 10 such as Ag plating having a low resistivity as the outer layer, It is easy to flow the current applied by the surge, and the melting due to the self-heating can be prevented. Therefore, fuse element 2 can significantly improve the resistance to surge as compared to a fuse made of a conventional solder alloy.

The fuse element 2 can be manufactured by using a film forming technique such as electrolytic plating on the surface of the low melting point metal layer 9. For example, the fuse element 2 can be efficiently manufactured by performing Ag plating on the surface of solder foil or thread solder. Further, as shown in FIG. 6A, the fuse element 2 may have a laminated structure in which the high melting point metal layer 10 is laminated on the upper and lower surfaces of the low melting point metal layer 9, as shown in FIG. The low melting point metal layer 9 is treated by electrolytic plating, electroless plating and the like, and then cut into a predetermined length so that the low melting point metal layer 9 faces from both end faces and the outer periphery is covered with the high melting point metal layer 10 It is good also as a covering structure. In the present technology, the structure of the fuse element 2 is not limited to that shown in FIG.

Preferably, in the fuse element 2, the volume of the low melting point metal layer 9 is larger than the volume of the high melting point metal layer 10. The fuse element 2 can etch the high-melting point metal by melting the low-melting point metal by self-heating, and can thereby rapidly melt and melt it. Therefore, fuse element 2 promotes this corrosion action by forming the volume of low melting point metal layer 9 more than the volume of high melting point metal layer 10, and rapidly cuts off between

terminal portions

2a and 2b. Can.

[Deformation control section]
Further, as shown in FIG. 7, the fuse element 2 may be provided with a deformation restricting portion 6 which suppresses the flow of the melted low melting point metal and restricts the deformation. As a result, it is possible to suppress the deformation due to the flow of the low melting point metal at the time of reflow heating or the like and prevent the fluctuation of the melting characteristic even in the fuse element 2 which is increased in rating and lowered in resistance by increasing the area.

The deformation restricting portion 6 is provided on the surface of the fuse element 2, and as shown in FIG. 7, at least a part of the side surface of one or more holes 12 provided in the low melting point metal layer 9 is the high melting point metal layer 10. And a continuous second high melting point metal layer 14. The holes 12 can be formed, for example, by piercing a low-melting point metal layer 9 with a pointed object such as a needle, or pressing the low-melting point metal layer 9 using a mold. In addition, the shape of the hole 12 may be, for example, an oval, a rectangle, or any other shape. Further, the holes 12 may be formed in the central portion to be the fused portion of the fuse element 2 or may be formed uniformly over the entire surface. In addition, by forming the holes 12 at positions corresponding to the melting portion, the amount of molten metal in the melting portion can be reduced and the resistance can be increased, and the heating and melting can be performed more quickly.

The material forming the second high melting point metal layer 14 has a high melting point that does not melt depending on the reflow temperature, like the material forming the high melting point metal layer 10. The second refractory metal layer 14 is preferably formed of the same material as the refractory metal layer 10 in the step of forming the refractory metal layer 10 in terms of production efficiency.

[flux]
The fuse element 1 is a flux not shown on the front or back surface of the fuse element 2 for preventing oxidation of the high melting point metal layer 10 or the low melting point metal layer 9 and removing oxides during melting and improving solder fluidity. May be coated.

Even when an oxidation preventing film such as Pb-free solder containing Sn as a main component is formed on the surface of the high melting point metal layer 10 of the outer layer by coating the flux, the oxide of the oxidation preventing film is removed. As a result, the oxidation of the refractory metal layer 10 can be effectively prevented, and the melting characteristics can be maintained and improved.

[Fuse blowout]
Such a fuse element 1 has a circuit configuration shown in FIG. 8 (A). The fuse element 1 is mounted on the external circuit through the

terminal portions

2a and 2b, and is incorporated on the current path of the external circuit. While a predetermined rated current flows through fuse element 2, fuse element 1 is not melted even by self-heating. Then, in the fuse element 1, when an overcurrent exceeding the rated current flows, the fuse element 2 melts due to the occurrence of arc discharge due to self-heating of the fuse element 2 and cuts off between the

terminal portions

2a and 2b. Cut off the current path of the circuit (FIG. 8 (B)).

At this time, the fuse element 1 has the resin portion 4 for capturing the molten scattered matter 11 of the fuse element 2 on at least a part of the inner wall surface 8 a of the case 3 accommodating the fuse element 2. By being captured in a discontinuous state in the portion 4, continuous adhesion to the inner wall surface 8 a reaching both ends of the fuse element 2 in the current supply direction can be prevented. Therefore, fuse element 1 can prevent a situation in which both ends of fuse element 2 fused and cut by the melt spatter 11 of fuse element 2 continuously adhering to inner wall surface 8 a of case 3 are shorted.

[Modification of fuse element]
Next, modifications of the fuse element to which the present technology is applied will be described. In the following description, the same components as those of the fuse element 1 described above are denoted by the same reference numerals and the details thereof will be omitted. In the fuse element 20 to which the present invention is applied, as shown in FIGS. 9A and 9B, the base member 21, the fuse element 2 mounted on the surface 21 a of the base member 21, and the fuse element 2 are mounted. And a cover member 22 constituting an element housing 28 for covering the fuse element 2 with the base member 21.

The fuse element 20 corresponds to the case 3 in which the element housing 28 constituted by the base member 21 and the cover member 22 accommodates the fuse element 2 described above. The element housing 28 is formed with an outlet 7 for leading out the pair of

terminal portions

2 a and 2 b outside the element housing 28 formed by joining the base member 21 and the cover member 22. The fuse element 2 is connectable to the connection electrode of the external circuit through the

terminal portions

2 a and 2 b led out from the lead-out port 7.

The base member 21 can be formed of the same material as that of the case 3 described above, and is formed of, for example, an engineering plastic such as liquid crystal polymer, an insulating member such as alumina, glass ceramics, mullite, or zirconia. In addition, the base member 21 may be made of a material used for a printed wiring board such as a glass epoxy substrate or a phenol substrate.

Similar to the base member 21, the cover member 22 can be formed of the same material as that of the case 3 described above, and can be formed of, for example, an insulating member such as various engineering plastics and ceramics. The cover member 22 is connected to the base member 21 via, for example, an insulating adhesive, or is connected by providing a fitting mechanism between the cover member 22 and the base member 21.

Further, as shown in FIG. 9B, in the base member 21, a groove 23 is formed on the surface 21 a on which the fuse element 2 is mounted. The cover member 22 also has a groove 29 formed to face the groove 23. As shown in FIGS. 10A and 10B, the

groove portions

23 and 29 are spaces where the fuse element 2 melts and shuts off, and in the fuse element 2, portions located in the

groove portions

23 and 29 have a thermal conductivity By contacting with low air, the temperature rises relatively to the other parts in contact with the base member 21 and the cover member 22, and it becomes the fused part 2c to be fused.

Further, the resin member 4 described above is formed on at least a portion of the inner wall surface of the groove portion 23, and the resin portion 4 described above is formed on at least a portion of the inner wall surface of the groove portion 29. Since the fuse element 2 is covered with the

grooves

23 and 29 in the fuse element 20, the molten metal is captured by the resin portion 4 even at the time of self heat generation interruption accompanied by the occurrence of arc discharge due to excessive current to prevent scattering to the surroundings. it can. In addition, fuse element 20 prevents melting and scattering material 11 of fuse element 2 from being trapped by resin portion 4 in a discontinuous state and preventing it from continuously adhering to the inner wall surface extending to both ends in the energization direction of fuse element 2. can do. Therefore, fuse element 20 can prevent a situation in which both ends of fuse element 2 fused and cut are short-circuited by melting and scattering material 11 of fuse element 2 continuously adhering to the inner wall surfaces of

groove portions

23 and 29. .

The resin portion 4 is formed continuously along the longitudinal direction of the

groove portions

23 and 29, faces the entire width of the fuse element 2, and has a length equal to or more than the entire width of the fuse element 2. Further, it is preferable that the resin portion 4 is also formed on the bottom surface and the bottom surface covering the entire length in the longitudinal direction of the

groove portions

23 and 29 and each side surface adjacent to the bottom surface on four sides.

A conductive adhesive or solder may be appropriately interposed between the base member 21 and the fuse element 2. Since the fuse element 20 is connected between the base member 21 and the fuse element 2 through an adhesive or solder, mutual adhesion is enhanced, and heat is more efficiently transmitted to the base member 21 and relatively. The fusing part 2c can be heated and fused.

In the fuse element 20, the first electrode 24 and the second electrode 25 may be provided on the surface 21a of the base member 21 instead of providing the groove 23 in the base member 21 as shown in FIG. The first and

second electrodes

24 and 25 are each formed of a conductive pattern such as Ag or Cu, and the surface is appropriately plated with Sn, Ni / Au, Ni / Pd, Ni / Pd /, etc. A protective layer such as Au plating may be provided.

The fuse element 2 is connected to the first and

second electrodes

24 and 25 via solder for connection. Since the fuse element 2 is connected to the first and

second electrodes

24 and 25, the heat radiation effect at the portion excluding the fusing part 2c is enhanced, and the fusing part 2c can be more effectively heated and fused.

Also in the configuration shown in FIG. 11, the resin portion 4 is formed on the base member 21 and the cover member 22. At this time, it is preferable that an air gap be formed between the resin portion 4 and the fuse element 2, but even when the resin portion 4 and the fuse element 2 are in contact with each other, the resin portion 4 has the first and second Since the thermal conductivity is lower than that of the

electrodes

24 and 25, the fusing part 2c can be relatively heated and fused. Also in the configuration shown in FIG. 11, in the fuse element 20, the groove 23 may be provided in the base member 21, the groove 29 may be provided in the cover member 22, and the resin portions 4 may be provided in the

grooves

23 and 29, respectively.

Further, instead of providing the

terminal portions

2a and 2b in the fuse element 2, or as shown in FIG. 12, the fuse element 20 performs the first and second on the back surface 21b of the base member 21 together with the

terminal portions

2a and 2b. First and second

external connection electrodes

24 a and 25 a electrically connected to the

electrodes

24 and 25 may be provided. The first and

second electrodes

24 and 25 and the first and second

external connection electrodes

24 a and 25 a are electrically connected through the through holes 26 penetrating the base member 21 and castellation. The first and second

external connection electrodes

24a and 25a are also formed of conductive patterns such as Ag and Cu, respectively, and Sn plating, Ni / Au plating, Ni / Pd plating, Ni / Pd plating, Ni / Au plating as appropriate for preventing oxidation. A protective layer such as Pd / Au plating may be provided. The fuse element 20 is mounted on the current path of the external circuit board via the first and second

external connection electrodes

24a and 25a instead of the

terminal parts

2a and 2b or together with the

terminal parts

2a and 2b.

In the fuse element 20 shown in FIGS. 11 and 12, the fuse element 2 is mounted apart from the surface 21 a of the base member 21. Accordingly, the fuse element 20 is melted between the first and

second electrodes

24 and 25 without the molten metal biting into the base member 21 even when the fuse element 2 is melted, which is combined with the effect of the resin portion 4 described above The insulation resistance between the

terminal portions

2a and 2b and between the first and

second electrodes

24 and 25 can be reliably maintained.

The fuse element 20 is a flux not shown on the front or back surface of the fuse element 2 for preventing oxidation of the high melting point metal layer 10 or the low melting point metal layer 9 and removing oxide during melting and improving solder fluidity. May be coated.

[Terminal]
Further, as shown in FIG. 9, the fuse element 20 may refract the

terminal portions

2 a and 2 b of the fuse element 2 led to the outside of the case 3 along the side surface of the base member 21. The fuse element 2 is fitted to the side surface of the base member 21 by bending the

terminal portions

2a and 2b, and the

terminal portions

2a and 2b are directed to the bottom surface side of the base member 21. As a result, the fuse element 1 can be surface mounted by setting the bottom surface of the base member 21 as the mounting surface and connecting the

terminal portions

2a and 2b with the connection electrodes of the external circuit board.

Further, by forming

terminal portions

2a and 2b in fuse element 2, fuse element 20 provides an electrode on the surface on which fuse element 2 of base member 21 is mounted, and is connected to the electrode on the back surface of base member 21. It is not necessary to provide an external connection electrode, and the manufacturing process can be simplified, and the current rating is not limited by the conduction resistance between the electrode of the base member 21 and the external connection electrode, and the fuse element 2 itself can The rating can be defined and the current rating can be improved.

The

terminal portions

2a and 2b are formed by bending the end portion of the fuse element 2 mounted on the surface of the base member 21 along the side surface of the base member 21 and appropriately bent one or more times outside or inside. It is formed by Thus, in the fuse element 2, a bent portion is formed between the substantially flat main surface and the bent end surface.

Then, when the

terminal portions

2a and 2b of the fuse element 20 are exposed to the outside of the element and mounted on the external circuit board, the

terminal portions

2a and 2b are connected to the connection electrodes formed on the external circuit board by solder or the like. Thus, the fuse element 2 is incorporated into the external circuit.

[Heating element]
The present technology can also be applied to a fuse element 40 in which a heating element 41 is provided on a base member 21 as shown in FIGS. 13 (A) and 13 (B). In the following description, the same members as those of the

fuse elements

1 and 20 described above are denoted by the same reference numerals, and the details thereof will be omitted. The fuse element 40 to which the present invention is applied is laminated on the base member 21 and the base member 21 and the heating element 41 covered with the insulating member 42, the first electrode 24 formed on both ends of the base member 21 and The second electrode 25 is stacked on the base member 21 so as to overlap with the heating element 41, and the heating element lead-out electrode 45 electrically connected to the heating element 41, the first and second electrodes 24 at both ends. , 25 and the fuse element 2 whose central portion is connected to the heating element lead electrode 45. The fuse element 40 forms the element housing 28 by bonding or fitting the base member 21 and the cover member 22 to each other. Further, as described above, in the cover member 22, the resin portion 4 described above is formed on at least a part of the inner wall surface.

First and

second electrodes

24 and 25 are formed on the surface 21 a of the base member 21 at opposite ends. In the first and

second electrodes

24 and 25, when the heating element 41 is energized and generates heat, the fused fuse elements 2 gather due to the wettability thereof, and the

terminal portions

2 a and 2 b are melted and cut.

The heating element 41 is a member having conductivity that generates heat when current is supplied, and is made of, for example, nichrome, W, Mo, Ru, or a material containing these. The heating element 41 is formed by mixing the powdery substance of the alloy, the composition, or the compound with a resin binder or the like to form a paste, and forming a pattern on the base member 21 using a screen printing technique and baking it. And the like.

Further, in the fuse element 40, the heating element 41 is covered by the insulating member 42, and the heating element lead electrode 45 is formed so as to face the heating element 41 via the insulating member 42. The heat generating body lead electrode 45 is connected to the fuse element 2, whereby the heat generating body 41 is overlapped with the fuse element 2 via the insulating member 42 and the heat body lead electrode 45. The insulating member 42 is provided to protect and insulate the heat generating body 41 and efficiently transmit the heat of the heat generating body 41 to the fuse element 2, and is made of, for example, a glass layer.

The heating element 41 may be formed inside the insulating member 42 stacked on the base member 21. The heating element 41 may be formed on the back surface 21 b opposite to the surface 21 a of the base member 21 on which the first and

second electrodes

24 and 25 are formed, or on the surface 21 a of the base member 21. It may be formed adjacent to the first and

second electrodes

24 and 25. In addition, the heating element 41 may be formed inside the base member 21.

The heating element 41 is connected to the heating element lead-out electrode 45 via the first heating element electrode 48 formed on the surface 21 a of the base member 21 at one end, and the other end is on the surface 21 a of the base member 21. It is connected to the formed second heating element electrode 49. The heat generating body lead electrode 45 is connected to the first heat generating body electrode 48 and superimposed on the heat generating body 41 so as to be stacked on the insulating member 42 and connected to the fuse element 2. Thus, the heating element 41 is electrically connected to the fuse element 2 through the heating element lead electrode 45. The heating element lead-out electrode 45 is disposed so as to overlap the heating element 41 with the insulating member 42 interposed therebetween, whereby the fuse element 2 can be melted and the molten conductor can be easily aggregated.

In addition, the second heat generating electrode 49 is formed on the surface 21 a of the base member 21 and is formed on the back surface 21 b of the base member 21 through castellation (see FIG. 14A). And is continuous.

The fuse element 40 is connected across the second electrode 25 from the first electrode 24 through the heating element lead electrode 45. The fuse element 2 is connected on the first and

second electrodes

24 and 25 and the heating element lead electrode 45 via a connection material such as connection solder.

[flux]
In addition, the fuse element 40 prevents the oxidation and sulfurization of the high melting point metal layer 10 or the low melting point metal layer 9, removes oxides and sulfides at the time of melting and improves the flowability of the solder. The back side may be coated with flux 47. By coating the flux 47, the wettability of the low melting point metal layer 9 (for example, solder) is enhanced at the time of actual use of the fuse element 40, and oxides and sulfides are removed while the low melting point metal is dissolved. In addition, it is possible to improve the melting characteristics by using the corrosion action on high melting point metals (for example, Ag).

In addition, even when an oxidation preventing film such as Pb-free solder mainly composed of Sn is formed on the surface of the outermost high melting point metal layer 10 by coating the flux 47, the oxide of the oxidation preventing film Can be removed, oxidation and sulfurization of the high melting point metal layer 10 can be effectively prevented, and fusing characteristics can be maintained and improved.

The first and

second electrodes

24 and 25, the heating element lead electrode 45, and the first and second

heating element electrodes

48 and 49 are formed of a conductive pattern such as Ag or Cu, for example, and Sn is appropriately formed on the surface. It is preferable that a protective layer such as plating, Ni / Au plating, Ni / Pd plating, Ni / Pd / Au plating, etc. is formed. Thus, oxidation and sulfurization of the surface can be prevented, and corrosion of the first and

second electrodes

24 and 25 and the heating element lead electrode 45 by the connection material such as the connection solder of the fuse element 2 can be suppressed. .

In addition, the fuse element 40 constitutes a part of the conduction path to the heating element 41 by connecting the fuse element 2 to the heating element lead electrode 45. Therefore, when the fuse element 2 is melted and the connection with the external circuit is cut off, the current path to the heat generating element 41 is also cut off, so that the heat generation can be stopped.

[circuit diagram]
The fuse element 40 to which the present invention is applied has a circuit configuration as shown in FIG. That is, the fuse element 40 is energized by generating heat via the fuse element 2 connected in series across the pair of

terminal portions

2 a and 2 b through the heating element lead electrode 45 and the fuse element 2 to generate heat. It is a circuit configuration comprising a heating element 41 for melting 2. The fuse element 40 is connected to the external circuit board with the heating element feed electrode 49a connected to the

terminal portions

2a and 2b provided at both ends of the fuse element 2 and the second heating element electrode 49. Thereby, in fuse element 40, fuse element 2 is connected in series on the current path of the external circuit through

terminal portions

2a and 2b, and the heating element 41 is a current provided in the external circuit through heating element power supply electrode 49a. It is connected to the control element.

[Fuse blowout]
In the fuse element 40 having such a circuit configuration, when it is necessary to cut off the current path of the external circuit, the heating element 41 is energized by the current control element provided in the external circuit. As a result, in the fuse element 40, the heat generation of the heating element 41 melts the fuse element 2 incorporated on the current path of the external circuit, and the molten conductor of the fuse element 2 has a highly wettable heating element lead electrode 45 and The fuse element 2 is fused by being drawn to the first and

second electrodes

24 and 25. Thus, fuse element 2 is reliably fused between terminals 2a to heating element lead electrode 45 to terminal 2b (FIG. 14B), and the current path of the external circuit can be cut off. In addition, as the fuse element 2 is melted, the power supply to the heating element 41 is also stopped.

At this time, the fuse element 2 starts melting from the melting point of the low melting point metal layer 9 having a melting point lower than that of the high melting point metal layer 10 by the heat generation of the heating element 41 and starts to etch the high melting point metal layer 10. Therefore, in the fuse element 2, the high melting point metal layer 10 is melted at a temperature lower than the melting temperature by utilizing the erosion action of the high melting point metal layer 10 by the low melting point metal layer 9, and the current of the external circuit is rapidly reduced. You can block the path.

As described above, in the fuse element 40, the resin portion 4 is formed on at least a part of the inner wall surface of the cover member 22. Since the fuse element 2 is covered with the cover member 22 in the fuse element 40, the molten metal can be captured by the cover member 22 even when the self heat generation is interrupted with the occurrence of arc discharge due to an overcurrent, and scattering to the surroundings can be prevented. . In addition, fuse element 40 prevents melting and scattering material 11 of fuse element 2 from being trapped by resin portion 4 in a discontinuous state and preventing it from continuously adhering to the inner wall surface extending to both ends in the energization direction of fuse element 2. can do. Therefore, fuse element 40 can prevent a situation in which both ends of fuse element 2 fused and cut by the melt spatter 11 of fuse element 2 continuously adhering to the inner wall surface of cover member 22 are short circuited.

The fuse element 40 also forms the resin portion 4 between the first electrode 24 of the base member 21 and the insulating member 42 and between the second electrode 25 of the base member 21 and the insulating member 42. May be By forming the resin portion 4 between the insulating member 42 and the first and

second electrodes

24 and 25, the resin portion 4 also captures the molten scattered object 11 of the fuse element 2 in the region. can do.

The

fuse elements

20 and 40 described above are surface-mounted on the external circuit board by connecting the

terminal portions

2a and 2b of the fuse element 2 to external connection terminals provided on the external circuit board by soldering or the like. The

fuse elements

20 and 40 to which the present technology is applied can also be used for connections other than surface mounting.

For example, in the

fuse elements

20 and 40 to which the present technology is applied, the

terminal portions

2a and 2b of the fuse element 2 may be connected to a metal plate serving as an external connection terminal capable of handling a large current. The connection between the

terminal portions

terminal part

DESCRIPTION OF SYMBOLS 1 fuse element, 2 fuse element, 2a terminal part, 2b terminal part, 2c fused part, 3 cases, 4 resin parts, 6 deformation control part, 7 outlet port, 8 storage space, 8a inner wall surface, 9 low melting point metal layer, DESCRIPTION OF REFERENCE NUMERALS 10 high melting point metal layer, 11 melting and scattering material, 12 holes, 14 second high melting point metal layer, 20 fuse element, 21 base member, 21a surface, 21b back surface, 22 cover member, 23 groove portion, 24 first electrode, 24a first external connection electrode, 25 second electrode, 25a second external connection electrode, 26 through holes, 28 element housings, 29 grooves, 40 fuse elements, 41 heating elements, 42 insulating members, 45 heating element drawers Electrode, 47 flux, 48 first heating electrode, 49 second heating electrode, 49a heating electrode

Claims

Fuse element,
And a case for housing the fuse element;
The case is a fuse element having a resin portion whose surface is melted by heat accompanying melting of the fuse element on at least a part of the inner wall surface facing the inside which accommodates the fuse element.
Fuse element,
And a case for housing the fuse element;
The case is a fuse element having a resin portion which captures the molten scattered matter of the fuse element on at least a part of the inner wall surface facing the inside which accommodates the fuse element.
The fuse element according to claim 2, wherein the molten scattered matter captured by the resin portion is in a discontinuous state.
The fuse element according to any one of claims 1 to 3, wherein the resin portion is formed using a nylon-based or fluorine-based resin material.
The fuse element according to any one of claims 1 to 3, wherein the case is formed of a ceramic material.
The fuse element according to any one of claims 1 to 3, wherein the resin portion is made of a material having a tracking resistance of 250 V or more.
The fuse element according to any one of claims 1 to 3, wherein the resin portion is made of a material having a tracking resistance of 600 V or more.
The fuse element according to any one of claims 1 to 3, wherein the resin portion is made of a material having a melting point of 400 ° C or less.
The fuse element according to any one of claims 1 to 3, wherein the resin portion is made of a material having a thermal conductivity of 1 W / m · K or less.
The fuse element according to any one of claims 1 to 3, wherein the case supports two places separated in the current-flowing direction of the fuse element, and hollowly supports the supported portions.
11. The fuse element according to claim 10, wherein the resin portion is formed in the case so as to block between the supported portions of the inner wall in a direction orthogonal to the current-flowing direction of the fuse element.
The fuse element according to any one of claims 1 to 3, wherein the resin portion is formed on the entire surface of the inner wall surface.
The fuse element according to any one of claims 1 to 3, wherein the fuse element is a laminate in which the inner layer is a low melting point metal layer and the outer layer is a high melting point metal layer.
Equipped with a heating element,
The fuse element according to any one of claims 1 to 3, wherein the fuse element is melted down by heat generation caused by the energization of the heat generating element.